Prefocused lamp base



June 8, 1937 D. s. Gus-11N I PREFOUSED LAMP 'BASE Filed Deo. 1,6,` 1935ATTORNEY INVENTOR f- ..`5'. 6057"/ v1.iil Mu nl BYM Patented June 8,1937 PnErooUsEn LAMP BASE Daniel S. Gustin,I East Orange, N. J.,assixnor, by mesne assignments, to Westinghouse Electric andManufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania t Application December 16, 1933, Serial No. 702,691

9 Claims.

This invention relates to electrical devices and particularly to anincandescent electric lamp A in which the light source is disposed in apredetermined position relative to other parts ofthe device.'

Certain types of electric incandescent lamps termed precision lamps areused with special holding means to position the filament of the lamp ona given focal line as in the most effective position with respect to areiiector. The light source of the lamp must be accurately located andsince it is necessary to interchange or replace a burned out lamp with anew lone it is important that the lamps are so manufactured that theillament in each lamp occupies the same relative position.

Heretofore lamps have been made with the usual manufacturing accuracyand means have been provided in the sockets or holders for the necessaryadjustment. In other cases the usual brass shell/base has been used andadjusted prior to permanent attachment to thebulb or a ilanged ring hasbeen used which ring was sol-r the course of manufacturing largequantities oi?l lamps that some lamps will be produced in which theiilaments are located with a considerable degree of accuracy but inorder to insure a more uniform product in the form of alamp which mayb'e used for optical purposes it is lnecessary that each lamp be soconstructed that the illament will be positively positioned with respectto another point on the bulb or base ofthe lamp.

An object of the present invention is, therefore, to provide a method ofmanufacturing an incandescent electric lamp in such a manner as to meetthe usual practice in lamp production and produce a lamp with theillament definitely positioned with respect to the base of the bulb.Another object of the invention is to provide va lamp with a base oi'molded material so formed as to provide a surface in predeterminedrelation to the lamp iilament. .I

Other objects and advantages of the invention will be more clearlyunderstood by reference to the following description together with theac-` companying drawing in which Fig. 1 is a side elevational view of alamp constructed in accordance with the present invention disposed abovea'holder or socket; 5

Fig. 2 is an enlarged sectional view of the lamp shown in Fig. 1 butpositioned in a holder or socket;

Fig. 3 is a view looking toward the bottom of the lamp; I 10 Fig. 4 is across-sectional detail view of a mold for forming a base in accordancewith the present invention;

Fig. 5 is a view partly in cross section showing a bulb .in position tohave a base molded thereon 15 and Fig. 6 is a view similar to Fig. 5 butshows the molding material disposed about the bulb to form a base. v

Although the present invention is particularly 20 desirable for themanufacture of a'lamp with the filament denitely positioned with respectto a given surface or projection on the base it may also be applied tothe manufacture of lamps of other types or may be practiced forproviding 25 a base for vacuum devices in general where it is desirableto provide a base of insulative material.

As illustrated in the drawing the present invention may be employed toprovide a base for 30 a lamp to be used as a light source for anautomobile headlight.

As shown, a lamp of this character may comprise a bulb I0 provided witha lament I I having its terminals secured to the ends of conductive 35support wires I2 and I3. These support wires extend through a press I4(see Fig. 2) and from the bulb in the form of extensions orlead wiresI5A and I irespectively.

These lead wires are connected to contact 40- wires to the contacts.

Incandescent electric lamps as commonly constructed include a are tubeI1 which extends into the bulb, carries the press I4; and is sealed 50 Iat IB tothe neck of the bulb, a tube I9 being provided for the purposeof exhausting the bulb. It is the practice in lamp manufacture toprovide a mount which includes the flare tube having support wires.containing lead wires sealed 55 through the press, and having afilament secured to the support Wires. This mount is then supported anda bulb is disposed so that its neck surrounds a flanged portion of theflare tube. Heat isvthen applied and the flare tube sealed to the bulb,leaving a bead or annulus 2l The sealing-in operation is performed withas much accuracy as is possible under high speed conditions and thelament located in a denite position Within relatively narrow limits.When a base is applied to the bulb, however, it is not always possibleto exactly position it a definite distance from the filament, nor is itpossible to provide bases, unless special care is exercised, which donot have variations in their physical dimensions. Auxiliary means asabove mentioned must, therefore, be provided to cooperate with a socketor holder to properly locate the filament. l

In accordance with the present invention a base is provided by molding'from a suitable insulative material and during the molding of the basea surface is rprovided a definite distance from the filament, whichsurface cooperates with a holder or socket to locate the filament inproper focal relation with a reflector or other optical system.

As shown in Figs. 4 to 6, a mold 22 may be provided, including a chamber23 in which a plunger 24 is disposed for movement along the longitudinalaxis of the chamber. The plunger may be provided with apertures 25 and26 to receive tubular contact members 21 and 28. apertures may beenlarged to receive and seat the contacts, Which latter may haveenlarged ends or heads which project above the upper end of the plunger.terial may be placed in the chamber above the plunger and may be soformed as to provide space for the ends of the contacts. The moldablematerial may be of such character that before curing by heat it is inthe form of a plastic mass and the chamber 23 may be provided with asteam jacket 3l into which live steam is admitted to set or cure themoldable material after it has been shaped by pressure resulting from amovement of the plunger 24.

A sealed-in bulb I0 may be disposed, as shown in Figs. 5 and 6, with theneck thereof inserted into the upper end of the chamber 23 and may beheld by jaws 32 and 33 and pressure cap 34. The chamber may be providedwith an annular recess 35. The lead wires l5 and I6 may be threaded intothe contacts and extend into the apertures in the plunger. The plungermay then be moved to compress the moldable material into the form of abase, as shown in Fig. 6,

`at which time the heads of the contacts become embedded and thussecured in the moldable material when heat is applied and the materialhas hardened. The bead 2l holds the bulb securely to the base. Ifdesirable, the bulb may have depressions or protuberances formed in theglass to insure a more secure hold.

The base, by reason of the annular recess 35, is provided with ashoulder 36, the -lo-wer surface 31 of which may be a denite distancefrom the light source I|.` 'Ihis surface cooperates with a surface 38 ofa holder or socket 39 and contact 21 may have a notch 4I to engage atension member 42 on the holder which maintains the surface 31. of thebase against the surface 38 of the holder. The contact 28 may engageanother contact insulated from the tension member. The holder shown isgiven one means of The' A pellet 29 of a moldable maholding the lamphaving the present form of base, but it is obvious that the constructionof the holder may vary to meet the requirements of the particular typeof equipment in which the lamp is to be used.

It will be evident that, when molding bases onto the necks of bulbs,variations may occur causing the bulbs to be held at slightly differentpositions in the mold depending on the accuracy of the diameter of thebulb at the contact surface M Where it seats on the mold. 'I'he recesswhich forms the shoulder is, therefore, so arranged `that the distance Xbetween the light and the shoulder on the base resulting from therecess, is greater than the distance required. When the bulb has beenprovided with a base it is supported for rotation and a tool d5 isemployed to trim material from, the shoulder until a surface on the baseis provided at a predetermined distance from the light source. 'Ihetrimming operation may be made with optical means 46 so that an operatormay trim oil the proper amount of material.

The lamp may, however, be used in a socket or holder in whichv a xedsurface is provided to engage the bottom surface 4l of the base. In thiscase the plunger may be so controlled that the distance Y is apredetermined dimension. As above pointed out the lamps are made with a.considerable degree of accuracy and it is only necessary to vary thesurface on the base a very small fraction of an inch usually between eand V64 of an inch so that the plunger may press the moldable materialto form a complete base but may be arrested during the compressingoperation so that the bottom surface of the base is located apredetermined distance from the light source.

When forming the base to provide the surface d1 in the required relationto the light source, suitable optical means may be employed such forexample as shown in my Patent 1,760,693 issued May 27, 1930. It will beevident that by reason of the present method of forming a base on a bulbthe bulb may, prior to the molding operation, be adjusted laterally tobring the lament into vertical focal position.

When a lamp with a base molded thereon is removed from the mold the leadwires may be cut olf `flush with the ends of the contacts and solderedthereto.

The lamp is then ready to be used with any reector or optical systemwherein the most advantageous results are obtained when the light sourceis in a definite position with respect to a given focal line.

Although a preferred embodiment of the invention 1s shown and describedherein it is to be understood that modifications may be made thereinwithout departing from the spirit and scope of the invention as setforth in the appended claims.

What is claimed is:

1. An incandescent lamp comprising a bulb, a :lamentin said bulb, a baseentirely of material molded around the neck of the bulb, said base beingshaped to fit a socket and to provide an external surface of said moldedmaterial a predetermined distance from said lament, and contact membersembedded in said molded material and adapted to cooperate with saidsocket to hold said surface in engagement with a positioning surface onsaid socket.

2. An incandescent lamp comprising a bulb, a filament in said bulbpositioned with the usual commercial accuracy, a base of material moldedaround the neck of said bulb, said base having a shoulder of said moldedmaterial formed thereon a predetermined distance from said filament andextending as an annular surface entirely therearound, said shoulderbeing adapted to engage with a socket member and to position thefilament in a definite space relation thereto, and contact membersembedded in said molded material for holding said shoulder in placeagainst a corresponding surface on said socket member, by en.

`from said molded material and adapted to engage means carried by saidsocket member for holding said shoulder in engagement with said socketmember.

4. An incandescent lamp comprising a bulb, a filament in said bulbpositioned with the usual commercial accuracy, a base of material moldedaround the neck of said bulb, said base being shaped to fit a socketmember and having a contact portion formed of said molded material, sodisposed with respect to said filament as to cooperate with means on4said socket member to hold the filament in a predetermined positionrelative to said socket member, and conductive contact means extendinglongitudinally from the lower surface of said base and adapted to securesaid lamp in position in said socket member by engaging a portionthereof.

5. The method of basing a lamp bulb having a filament positioned withthe usual commercial accuracy which comprises forming contact members,forming a locking surface on at least one ofsaid contact members,shaping moldable material about the bulb neck to form a base, pressing fa surface on said base during the shaping operation a predetermineddistance from said filament and simultaneously embedding the ends ofsaid contact members in said material.

6. The method of basing a lamp bulb having a lament therein and leadwires extending from the neck thereof which comprises forming tubularcontact members, making a notch in one of said members for engagingymeans for holding said bulb in position, threading the lead wires intosaid members, compressing moldable material about said bulb neck to forma base while embedding the ends of said contact members, and during theshaping operation forming a surface on said base a predetermineddistance from said filament.

7. vThe method of basing a lamp bulb having a filament positioned withthe usual commercial accuracy which comprises supporting a bulb, formingconductive contact members, making a notch in at least one of saidmembers for interlocking with an associated lamp socket, shapingmoldable material about said contact members and bulb neck to form abase, adjusting the bulb with respect to the moldable material duringthe shaping operation to locate the filament in a predetermined positionwith respect to a surface formed during the shaping operation on saidbase, and permitting said material to harden to provide a surface toengage with asurface on said socket member to hold the filament in adesired relation with respect thereto.

8. The method of basing a lamp bulb having a lament positioned thereinwith the usual commercial accuracy which comprises, forming contactmembers and shaping at least one so as to lock said bulb in place, andshaping moldable material around the bulb neck and contact members soAthat an annular shoulder is provided extending entirely around saidbase and adapted tof engage the edge portion of a receiving socket.

9. The method of basing a. lamp bulb having a filament thereinpositioned with the usual commercial accuracy which comprises, shapingmoldable material about the bulb neck to form a .from said shoulder,while observing the position of the lament. until said shoulder ispositioned and at the `proper distance from said filament,

so that when the base is fitted in a receiving sock? et the filamentwill be disposed in the desired i location.

DANIEL s. GUSTIN.

